A dispenser for a predetermined dispensing ratio is disclosed in European Patent No. 492,413, according to which the drive shaft of the mixer is manually displaceable in the axial direction in order to couple or uncouple the mixer. U.S. Pat. No. 4,981,241 discloses an appliance allowing to dispense cartridges of different dispensing ratios and accordingly of variable cartridge diameters in one and the same dispenser, which is only designed for static mixers, however.